content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2012, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it 
   * under the terms of the GNU Lesser General Public License as published by 
   * the Free Software Foundation; either version 2.1 of the License, or 
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but 
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
   * USA.  
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
   * Other names may be trademarks of their respective owners.]
   *
   * ------------------
   * HashUtilities.java
   * ------------------
   * (C) Copyright 2006-2012, by Object Refinery Limited;
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes
   * -------
   * 03-Oct-2006 : Version 1 (DG);
   * 06-Mar-2007 : Fix for hashCodeForDoubleArray() method (DG);
   * 13-Nov-2007 : Added new utility methods (DG);
   * 22-Nov-2007 : Added hashCode() method for 'int' (DG);
   * 05-Dec-2007 : Added special methods to handle BooleanList, PaintList,
   *               and StrokeList (DG);
   * 15-Jun-2012 : Removed JCommon dependency (DG);
   *
   */
  
  package org.jfree.chart;
  
  import java.awt.GradientPaint;
  import java.awt.Paint;
  import java.awt.Stroke;
  
  import org.jfree.chart.util.BooleanList;
  import org.jfree.chart.util.PaintList;
  import org.jfree.chart.util.StrokeList;
  
  /**
   * Some utility methods for calculating hash codes.  
   * 
   * @since 1.0.3
   */
  public class HashUtilities {
      
      /**
       * Returns a hash code for a <code>Paint</code> instance.  If 
       * <code>p</code> is <code>null</code>, this method returns zero.
       * 
       * @param p  the paint (<code>null</code> permitted).
       * 
       * @return The hash code.
       */
      public static int hashCodeForPaint(Paint p) {
          if (p == null) {
              return 0;
          }
          int result = 0;
          // handle GradientPaint as a special case
          if (p instanceof GradientPaint) {
              GradientPaint gp = (GradientPaint) p;
              result = 193;
              result = 37 * result + gp.getColor1().hashCode();
              result = 37 * result + gp.getPoint1().hashCode();
              result = 37 * result + gp.getColor2().hashCode();
              result = 37 * result + gp.getPoint2().hashCode();
          }
          else {
              // we assume that all other Paint instances implement equals() and
              // hashCode()...of course that might not be true, but what can we
              // do about it?
              result = p.hashCode();
          }
          return result;
      }
      
      /**
       * Returns a hash code for a <code>double[]</code> instance.  If the array
       * is <code>null</code>, this method returns zero.
       * 
       * @param a  the array (<code>null</code> permitted).
       * 
       * @return The hash code.
       */
      public static int hashCodeForDoubleArray(double[] a) {
          if (a == null) { 
              return 0;
          }
          int result = 193;
          long temp;
          for (double anA : a) {
              temp = Double.doubleToLongBits(anA);
              result = 29 * result + (int) (temp ^ (temp >>> 32));
          }
          return result;
      }
      
      /**
       * Returns a hash value based on a seed value and the value of a boolean
       * primitive.
       * 
       * @param pre  the seed value.
       * @param b  the boolean value.
       * 
       * @return A hash value.
       * 
       * @since 1.0.7
       */
      public static int hashCode(int pre, boolean b) {
          return 37 * pre + (b ? 0 : 1);
      }
      
      /**
       * Returns a hash value based on a seed value and the value of an int
       * primitive.
       * 
       * @param pre  the seed value.
       * @param i  the int value.
       * 
       * @return A hash value.
       * 
       * @since 1.0.8
       */
      public static int hashCode(int pre, int i) {
          return 37 * pre + i;
      }
  
      /**
       * Returns a hash value based on a seed value and the value of a double
       * primitive.
       * 
       * @param pre  the seed value.
       * @param d  the double value.
       * 
       * @return A hash value.
       * 
       * @since 1.0.7
       */
      public static int hashCode(int pre, double d) {
          long l = Double.doubleToLongBits(d);
          return 37 * pre + (int) (l ^ (l >>> 32));
      }
      
      /**
       * Returns a hash value based on a seed value and a paint instance.
       * 
       * @param pre  the seed value.
       * @param p  the paint (<code>null</code> permitted).
       * 
       * @return A hash value.
       * 
       * @since 1.0.7
       */
      public static int hashCode(int pre, Paint p) {
          return 37 * pre + hashCodeForPaint(p);
      }
  
      /**
       * Returns a hash value based on a seed value and a stroke instance.
       * 
       * @param pre  the seed value.
       * @param s  the stroke (<code>null</code> permitted).
       * 
       * @return A hash value.
       * 
       * @since 1.0.7
       */
      public static int hashCode(int pre, Stroke s) {
          int h = (s != null ? s.hashCode() : 0);
          return 37 * pre + h;
      }
  
      /**
       * Returns a hash value based on a seed value and a string instance.
       * 
       * @param pre  the seed value.
       * @param s  the string (<code>null</code> permitted).
       * 
       * @return A hash value.
       * 
       * @since 1.0.7
       */
      public static int hashCode(int pre, String s) {
          int h = (s != null ? s.hashCode() : 0);
          return 37 * pre + h;
      }
  
      /**
       * Returns a hash value based on a seed value and a <code>Comparable</code>
       * instance.
       * 
       * @param pre  the seed value.
       * @param c  the comparable (<code>null</code> permitted).
       * 
       * @return A hash value.
       * 
       * @since 1.0.7
       */
      public static int hashCode(int pre, Comparable c) {
          int h = (c != null ? c.hashCode() : 0);
          return 37 * pre + h;
      }
  
      /**
       * Returns a hash value based on a seed value and an <code>Object</code>
       * instance.
       * 
       * @param pre  the seed value.
       * @param obj  the object (<code>null</code> permitted).
       * 
       * @return A hash value.
       * 
       * @since 1.0.8
       */
      public static int hashCode(int pre, Object obj) {
          int h = (obj != null ? obj.hashCode() : 0);
          return 37 * pre + h;
      }
      
      /**
       * Computes a hash code for a {@link BooleanList}.  In the latest version
       * of JCommon, the {@link BooleanList} class should implement the hashCode()
       * method correctly, but we compute it here anyway so that we can work with 
       * older versions of JCommon (back to 1.0.0).
       * 
       * @param pre  the seed value.
       * @param list  the list (<code>null</code> permitted).
       * 
       * @return The hash code.
       * 
       * @since 1.0.9
       */
      public static int hashCode(int pre, BooleanList list) {
          if (list == null) {
              return pre;
          }
          int result = 127;
          int size = list.size();
          result = HashUtilities.hashCode(result, size);
          
          // for efficiency, we just use the first, last and middle items to
          // compute a hashCode...
          if (size > 0) {
              result = HashUtilities.hashCode(result, list.getBoolean(0));
              if (size > 1) {
                  result = HashUtilities.hashCode(result, 
                          list.getBoolean(size - 1));
                  if (size > 2) {
                      result = HashUtilities.hashCode(result, 
                              list.getBoolean(size / 2));
                  }
              }
          }
          return 37 * pre + result;
      }
  
      /**
       * Computes a hash code for a {@link PaintList}.  In the latest version
       * of JCommon, the {@link PaintList} class should implement the hashCode()
       * method correctly, but we compute it here anyway so that we can work with 
       * older versions of JCommon (back to 1.0.0).
       * 
       * @param pre  the seed value.
       * @param list  the list (<code>null</code> permitted).
       * 
       * @return The hash code.
       * 
       * @since 1.0.9
       */
      public static int hashCode(int pre, PaintList list) {
          if (list == null) {
              return pre;
          }
          int result = 127;
          int size = list.size();
          result = HashUtilities.hashCode(result, size);
          
          // for efficiency, we just use the first, last and middle items to
          // compute a hashCode...
          if (size > 0) {
              result = HashUtilities.hashCode(result, list.getPaint(0));
              if (size > 1) {
                  result = HashUtilities.hashCode(result, 
                          list.getPaint(size - 1));
                  if (size > 2) {
                      result = HashUtilities.hashCode(result, 
                              list.getPaint(size / 2));
                  }
              }
          }
          return 37 * pre + result;
      }
  
      /**
       * Computes a hash code for a {@link StrokeList}.  In the latest version
       * of JCommon, the {@link StrokeList} class should implement the hashCode()
       * method correctly, but we compute it here anyway so that we can work with 
       * older versions of JCommon (back to 1.0.0).
       * 
       * @param pre  the seed value.
       * @param list  the list (<code>null</code> permitted).
       * 
       * @return The hash code.
       * 
       * @since 1.0.9
       */
      public static int hashCode(int pre, StrokeList list) {
          if (list == null) {
              return pre;
          }
          int result = 127;
          int size = list.size();
          result = HashUtilities.hashCode(result, size);
          
          // for efficiency, we just use the first, last and middle items to
          // compute a hashCode...
          if (size > 0) {
              result = HashUtilities.hashCode(result, list.getStroke(0));
              if (size > 1) {
                  result = HashUtilities.hashCode(result, 
                          list.getStroke(size - 1));
                  if (size > 2) {
                      result = HashUtilities.hashCode(result, 
                              list.getStroke(size / 2));
                  }
              }
          }
          return 37 * pre + result;
      }
  }
  